1. Field of the Invention
The present invention relates to a method for detecting an antigen with use of an antibody and an enzyme.
2. Description of the Background Art
Patent Literature 1 discloses an enzyme immunoassay method. FIG. 2 shows a sandwich method, which is included in the enzyme immunoassay method.
As shown in FIG. 2, a support 107 has an antibody 108 on its surface. The sample containing an antigen 109 is supplied to the surface of the support to cause the antigen 109 to be bound specifically to the antibody 108. Subsequently, the sample containing the unreacted antigen 109 was removed by washing.
Next, a labeled-antibody 111 comprising an enzyme 110 which detects the antigen 109 is supplied to the surface of the support 107 to form the complex composed of the antibody 108, the antigen 109, and the labeled-antibody 111. Subsequently, the sample containing the unreacted labeled-antibody 111 was removed by washing.
Finally, a substrate 112 of the enzyme 110 is supplied to the surface of the support 107. The enzyme 110 reacts with the substrate 112 metabolically to form a product 113. The luminescence degree or light absorption degree of the product 113 is measured to detect the antigen 109 indirectly.
However, the sandwich method requires not only the antigen 108 but also the labeled-antibody 111 comprising the enzyme 110. It is necessary that the labeled-antibody 111 is supplied after the specific reaction between the antibody 108 and the antigen 109. Furthermore, the unreacted labeled-antibody 111 is required to be removed.